The Guardian reports Swansea University scientists say the proliferation of weirs, dams and culverts is now creating a threat to wildlife.
Near the mouth of the River Afan in Port Talbot, south Wales, a pair of seagulls were to be seen last week pecking in a leisurely way at a dead salmon lying on a gravel bank. It was an unusual sight. Salmon are rarely found in the Afan these days.
The scene may have been unexpected, but it nevertheless illustrates a growing problem, say researchers – one that already affects rivers across Europe and could pose even greater threats to habitats and wildlife in future.